This invention relates generally to locating a mobile user and, more particularly, relates to locating a user through visual observations made by the user.
An increasingly popular use of computing devices is to allow a user the ability to interact with their physical surroundings. For example, handheld computers can provide the user with information on topics of interest near the user, such as restaurants, copy centers, or automated teller machines. Similarly, laptop computers seek to allow a user to control devices located in close proximity to that laptop, such as a printer located in the same room. Additionally, specialized computing devices, such as navigational systems found in many automobiles seek to provide the user with directions based on the user""s current location. A necessary element of all of these applications is the ability to determine the location of the user.
Current systems for locating a user rely on extensive, and expensive, infrastructure to support the system. One well known system for determining location is the Global Positioning System (GPS). GPS is a satellite based system in which the receiver, carried by the user, requires a signal from at least four satellites to determine the location of the user. A similar system, known as E-911, relies on signals from a user""s cellular telephone to triangulate the user""s position. Two methods currently relied on by the e-911 system use either the angle of the arrival of the user""s signal, the time of arrival, or the time difference of arrival. Both the GPS system and the E-911 system require the installation and maintenance of expensive and dedicated infrastructure. GPS, for example, requires maintaining many satellites, and the E-911 system requires either the installation of directional antennas on the cell phone and base station, or specialized equipment at the base stations to provide time synchronization. In addition, the E-911 system may require the user to purchase a new cell phone. These systems also suffer from other drawbacks inherent in their design. For example, the GPS system does not work indoors or in locations, such as downtown areas, with significant obstructions to the signal paths between the user and the satellites and cellular telephone base stations. Similarly, the E-911 system requires that the cell phone be able to communicate with multiple base stations simultaneously.
Additional location determining systems can be used in confined areas, but they too suffer from the need to purchase and maintain dedicated infrastructure. One known system for determining the location of a user indoors is the Active Badge system, that uses infrared beacons and sensors located throughout an area to pinpoint the user""s location. Additional systems rely on wireless communication between a transmitter and detectors placed throughout the indoor environment. Such systems suffer from the same complex infrastructure problem as GPS or E-911. In either case, dedicated detection equipment must be installed throughout the indoor area. Because of the amount of infrastructure needed for even small areas, such systems cannot be scaled well to larger areas, such as a whole town or metropolitan area. Additionally, some of these systems, such as infrared based systems, can be impacted by environmental concerns, such as direct sunlight.
In addition to the above problems, some of the known systems for determining a user""s location suffer from privacy concerns. Specifically, the user""s position is determined by infrastructure that is exclusively controlled by a central authority. Thus, the central authority could use the system to determine the location of a user even when that user did not wish to learn their location, or did not wish to be located. Furthermore, because all of these systems rely on a central architecture, they all leave the user vulnerable to system outages when the infrastructure required is not properly operated or maintained by the central authority. Often, the user is simply forced to rely on human interaction to determine their location.
Accordingly, the present invention is directed to identifying the location of a user without relying on dedicated infrastructure and a central authority.
Additionally, the present invention is dedicated to identifying the location of a user based on landmarks or other visual cues visible to the user from their current position.
The present invention is likewise directed to providing a user with an accessible and efficient database of landmarks and other visual cues from which the user""s position can be determined.
For centuries, people have guided one another by landmarks and visual cues. For example, people will often identify intersections, not by the street names, but by the names of gas stations or stores located on that corner. Similarly, people often describe their position as relative to specific landmarks, rather than using a more accurate coordinate system. The present invention seeks to capitalize on this interaction to provide a more intuitive system for determining the location of a user, that does not require significant infrastructure, comprise the user""s privacy, or leave the user vulnerable to system-wide outages.
The present invention contemplates a database of landmarks in a given area, such as a metropolis or a shopping mall. The database can be textual, associating landmarks with descriptive terms commonly used to describe that landmark. Alternatively, or in addition, a three-dimensional topographical database of the environment can be used, which can provide information regarding the visibility of the landmark from various locations, as well as distinctive features that can be used to further specify the user""s location.
Because of the nature of location determination, the present invention anticipates a portable computing device to interface with the database and calculate the user""s position. While a textual database can be of a sufficiently small size to be wholly stored on the portable computing device, a three-dimensional topographical database may contain too much information to be stored, in its entirety, on the portable computing device. Various techniques can be used to reduce the size of the database to more easily accommodate the generally smaller storage capacities of storage devices used by portable computing devices. For example, the three-dimensional topographical database can be simplified by removing information the user is not likely to comment upon, such as the texture of a wall of the building, or the windows of the building. Instead, the model can be downgraded such that it consists merely of block shapes that provide a minimum of information while continuing to allow the computation of the visibility regions. Alternatively, a subsection of the three-dimensional topographical model can be downloaded to the portable computing device, and the remainder can be obtained from a server that has increased storage capacity and can store the whole model. The portable computing device can request specific information from the server, or it can merely listen to broadcast or multicast transmissions from the server providing additional information for a specific area or region. Similarly, a minimalist model, containing only the block shapes, can be used in conjunction with server communication, such that the server can be contacted to provide the features and elements, as needed, that were removed from the minimalist model.
With a portable computing device having access to a database of landmark information, the user can provide input that will enable the system to determine the user""s location. The portable computing device can be equipped with a pen-based or keyboard-based input device to accept computer-readable information from the user, or the device can be equipped with a microphone and speech interpreting software to accept vocal input. Using the appropriate input device, the user can describe, in varying degrees of specificity, what the user sees. Based on the description of the landmarks provided by the user, the portable computing device can access the database to determine the user""s location. If insufficient information was provided, or the information results in the determination of more than one unique location, the user can be prompted for more information. For example, the user can be prompted for specific information needed to resolve an ambiguity, or the user can be prompted for more information, generally, about their surroundings.
Once the portable computing device has been provided with the user""s input, it can compare the user""s descriptions of their surroundings to the database to identify the landmarks that the user is describing. Visibility regions, indicating those areas from which the landmark can be seen, can be calculated for each landmark identified, or for a more focused subset, such as those landmarks that have small visibility regions. If the intersection of the visibility regions yields only one location, then the system can return it as the user""s location. Alternatively, if the intersection of the visibility regions yields an area, or multiple areas with differing probabilities of likelihood, the system can prompt the user for more information. The user""s location can, therefore, be located by determining a location which uniquely matches the description provided by the user of their current surroundings.
Additional features and advantages of the invention will be made apparent from the following detailed description of illustrative embodiments that proceeds with reference to the accompanying figures.